Method of abrading a workpiece



Dec. 20, 1966 J. Y. SNYDER, 1 3,292,312

METHOD OF ABRADING A WORKPIECE Original Filed May 2, 1962 3 Sheets-Sheet l INVENTOR. John Q. m dex BYWY l Dec. 20, j Y S D METHOD OF ABRADING A WORKPIECE 3 Sheets-Sheet 2 Original Filed May 2 1962 I, III III 1' I'll 1 1, u I I I llIIIIlI-l I I I '11" INVENTOR john .L J E qder Dec. 20, 1966 J. Y. SNYDER 3,292,312

METHOD OF ABRADING A WORKPIECE Original Filed May 2, 1962 3 Sheets-Sheet 3 INVENTOR 33hr. w. Snqchzr BY W ATTORNEY United States Patent Ofitice 3,292,312 Patented Dec. 20, 1966 3,292,312 METHOD OF ABRADING A WORKPIECE John Y. Snyder, New Orleans, La., assignor of five percent to James H. Drury, five percent to Bernard M. Casimir, five percent to Rapier, Barre & Rapier, one and one-quarter percent to Mr. L. C. Lohman, one and one-quarter percent to Mrs. L. C. Lohrnan, five percent to Jake Polito, ten and one-half percent to Millard P. Snyder and eight percent each to Patricia S. Lancelotta, Elizabeth A. Snyder, Sara Jane Snyder and Mary J. Snyder Original application May 2, 1962, Ser. No. 191,834, now Patent No. 3,201,905, dated Aug. 24, 1965. Divided and this application Jan. 12, 1965, Ser. No. 432,926 3 Claims. (Cl. 51-281) This application is a divisional application of co-pending application Serial No. 191,834, filed May 2, 1962, now United States Patent No. 3,201,905, issued August 24, 1965.

The present invention relates to the art of lapping, grinding and/or abrading, and in particular provides a method in which a workpiece is moved orbitally over an active surface while being maintained in fixed orientation with portions thereof being alternately removed from contact with the active surface and returned to contact therewith.

In order to obtain fiat, smooth surfaces on various articles made of metal, such as brass or steel, it is known to abrade these articles against a suitable active surface, the term abrade here referring generally to and including grinding, lapping, polishing, etc. There have heretofore been provided various machines and methods for imparting a desired movement between the workpiece and the active surface, and exemplary movements utilized in the prior art include the rotation of an active surface against which the work-piece is held, and the rotation of the workpiece on an internal axis thereof, with the active surface either rotating or moving. The methods heretofore known, and the machines for practicing these methods, have not been able to produce articles of the desired flatness with a suitable high speed of production. Otherwise stated, where high speed of production was obtainable, the workpieces produced were not sutficiently flat, and on the other hand, an inordinate amount of time was required to produce workpieces which were suitably flat.

The active surfaces, or tables, so called, known to the prior art have drawn upon many materials, including resin plastics, thermoplastic resins and rubbery synthetic resins. These known substances have failed to provide surfaces which were satisfactory in that they wore out too quickly, were to slow, did not give a satisfactorily fiat surface to the workpiece, or were deficient for a plurality of these reasons.

In performing grinding, abrading and polishing operations, it is conventional to utilize various abrasive grain, jewelers rouge being a typical and well known polishing medium. The known mediums have not been satisfactory in all cases, sometimes resulting in scratching or galling the workpiece.

An object of the present invention is to provide an abrading method which will produce workpieces of a degree of flatness with relatively great speed.

Another object of the present invention is the provision of an abrading process which is simple and economical and which produces high quality workpieces in a short period of time.

Yet another object of the present invention is to provide a process which utilizes abrading elements, or tables, which will enable the production of high quality workpieces with great rapidity.

Other objects and many attendant advantages of the present invention will be readily understood from the following specification and drawings wherein:

FIGS. 1 to 5 are views illustrating the method in accordance with the present invention.

FIG. 6 is an elevational view of the construction shown in FIGS. 1 to 5.

FIG. 7 is a plan view illustrating the method of the invention being performed with a different workpiece.

FIG. 8 is an elevational view of a machine in accordance with the present invention.

FIG. 9 is a plan view of the machine of FIG. 8.

FIG. 10 is a cross-sectional view taken on the line 1010 of FIG. 8.

FIG. 11 is a cross-sectional view taken on the line 11-11 of FIG. 10.

FIG. 12 is a cross-sectional view taken on the line 1212 of FIG. 9.

FIG. 13 is a cross-sectional view taken on the line 1313 of FIG. 12.

FIG. 14 is a cross-sectional view similar to FIG. 11, showing another embodiment of the driver of the machine of the invention.

FIG. 15 is a view similar to FIG. 14 showing still another embodiment of a driver.

FIG. 16 is a cross-sectional view -of an abrading article in accordance with the invention.

' FIG. 17 is a cross-sectional view of another embodiment of an abrading article in accordance with the present invention.

FIG. 18 is a cross-sectional view showing abrasive applied to an a-brading article in accordance with the present invent-ion.

FIG. 19 is a cross-sectional view of another abrading article in accordance with the present invention.

Referring now to the drawings, wherein like or corresponding parts are designated by like or corresponding reference numerals throughout the several views, there is shown in FIG. 1 an abrading member 20 having an abrading surface 21. As may be seen in FIG. 6 the abrading member 20 may comprise a backup member 22 having a fiat sheet 23 thereon, the sheet 23 providing the surface 21. The backup member 22 and sheet 23 are of generally circular configuration, with the sheet 23 preferably having a beveled edge as at 24.

Concentric with the circular backup member 22 is a circular hub 26, so that there is thereby obtained an active abrading surface 21 which is annular and flat.

The workpiece is generally circular in plan form, as

may be seen in 'FIG. 1, and may be annular as shown.

To illustrate the invention, an indicating arrow has been placed on the workpiece W. Workpiece W has a diameter that is slightly greater than the difference between the major and minor diameters of the annular surface 21, so that workpiece W, when placed in abutting relationship with the hub 26, overhangs or extends beyond the edge of the abrading member 20. At least one-half of the workpiece contacts the surface 21.

With a suitable force pressing the workpiece W against the surface 21, workpiece W is revolved or moved in an orbital path about the center or imaginary central axis of abrading member 20, this being accomplished by maintaining the edge of workpiece W against the vertical surface of hub 26. Although the workpiece W is moved through an orbital path, as stated, it is not rotated about its own rotational axis, but instead is maintained in a substantially fixed orientation. As may be seen from FIG. 2, the workpiece W has moved through substantially in a clockwise manner, it being observed from the indicating arrow that the orientation of workpiece W has been substantially maintained. It will also be noted that work piece W overhangs or extends beyond the abrading member 20, but that a different portion of work-piece W now overhangs or extends beyond the edge or boundary of the abrading member 20. This will be seen by noting that in the FIG. 1 position, the part of the workpiece W beneath the arrow overhangs the abrading member 20, while in FIG. 2 that part of workpiece W now rests upon the surface 21, and another part, of crescent shape, overhangs the abrading member 20. In FIG. 3, the workpiece W has moved through another 90 of its orbit, the arrow showing that the orientation has been substantially maintained, and still another crescent-shaped portion of workpiece W overhangs the abrading member 20.

In FIG. 4, the workpiece W has moved through threefourths of one orbital movement, with still another portion of crescent shape overhanging the abrading member 20. In FIG. 5, the workpiece W is shown to have completed a single orbital movement, with the original crescent portion thereof which overhung the abrading member in FIG. 1 again overhanging the abrading member 20, but during the course of the movement having been in content with the abrading surface 21.

In FIG. 7 there is shown the abrading member 20' with a square workpiece, W, which is caused to move in substantially the manner described above, but without engaging a central hub and without overhanging the edge of workpiece W. The action and results obtained are otherwise the same as in FIGS. 1-6.

One machine for performing the method hereinabove described is shown in FIGS. 8 to 13, there being shown in FIGS. 8 and 9 an abrading machine having a base 31 with a motor 32 thereon connected by flexible driver 33 to a pulley 34. A shaft 35 on which pulley 34 is mounted extends into a gear box 36 to drive a gear train to which is connected a shaft 37 of a table 38, the gear train turning either slowly or intermittently. Table 38 is horizontally disposed and has an active abrading surface on the upper side thereof.

A standard 40 rises upwardly from base 31, supporting at its upper end a frame 41 and a motor 42, which latter has a sprocket 43. The frame 41 has an upper arm 44 and a pair of horizontal, spaced jaws 46 and 47. A splined spindle 48 passes vertically through the jaws 46 and 47, there being a sprocket 49 thereon which is held between the jaws 46 and 47. A chain 51 engages the sprockets 43 and 49 to provide rotation of spindle 48 by motor 42.

Extending upwardly from jaw 46 is a split cylinder 52, and an operating lever 53 is operatively connected with the spindle 48 through split cylinder 52, as will be described below. The lever 53 is pivoted to the upper part of arm 44.

At its lower end, below a collar 54 on spindle 48 is a :radially extending foot 55 having a drive member 56 extending downwardly through it. The drive member 56 is in engagement with the workpiece W, and passes through a ring 57 which is connected with a rod 58 having a pair of universal joints 59 and 61 therein. The distant I end of rod 58 is supported in a pair of sleeves 62 and 63, and uprights 64 and 65 serve to support these sleeves.

In FIGS. 10 and 11 it may be seen that foot 55 is made of two parts 66 and 67 held to the spindle 48 by bolts 68 and 69. A bolt 71 serves to hold a bushing 72 in position between parts 66 and 67, and as will be understood the position of the bushing along foot 55 may be varied. In FIG. 11, it will be seen that a pin 73 extends from the ring 57 through drive member 56.

To permit the insertion and removal of a workpiece W, spindle 48 has a reduced upper end 75 with screw threads 76, as may be seen in FIGS. 12 and 13. A thrust bearing 77 rests against the shoulder formed by reduced end 75, and a collar 78 having a circumferential groove 79 is held against the thrust bearing 77 by a nut 81 engaged with the threads 76. The lever 53 extends in a ring-like manner around the split cylinder 52, and has a pair of inwardly extending pins 82 and 83 entering through the longitudinal slots in split cylinder 52 and into the groove 79 of collar 78. A spring-loaded latch 84 mounted on lever 53 engages with a rack 85 on split cylinder 52.

In operation, the lever 53 is raised, and held in an elevated position by the engagement of latch 84 with rack 85.. This raises the spindle 48, foot 65 and drive member 56. The drive member 56 is positioned radially a suitable distance from spindle 48 for the particular workpiece Wv which is to be abraded, lapped, ground, etc. The workpiece W is then placed on table 38, with a suitable overhang as shown in FIGS. 9, 10 and 11. The lever 53 is lowered, latch 84 holding it down, so that drive member 56 presses against workpiece W, as shown. The motor 32 is energized to drive table 38, as described, and the motor 42 is energized to rotate spindle 48, foot 55, drive member 56 and workpiece W. As workpiece W orbits about the axis of spindle 48, it will be maintained in substantially the same orientation due to the ring 57, pin 73 and rod 58. The rod 58 can reciprocate in the sleeves 62 and 63,

and necessary flexing thereof will be permitted by the universal joints 59 and 61.

In FIG. 14, there is shown another embodiment of the driver of the abrading machine in which the spindle 48 has secured to it a foot 55 having a bore adjacent its outer receives a shaft 92 having a collar 93 thereon. Between collar 93 and the flange of bushing 91 is a thrust bearing 94, and a screw 95 acting through a lifting washer 96 1 serves to hold shaft 92 in bushing 91. Rod 58 is pivotally connected to shaft 92 by a pin 97, and the shaft 92 has a reduced threaded end 98 on which is a compression nut 99, which may be a wing nut. Slidably received on the end 98 is a drive member 100 to which is attached a flange 101, drive member 100 having a ball 102 fixed in its lower end which engages workpiece W. A compression spring 103 extends between the flange 101 and an abutment plate 104.

By means of the construction of FIG. 14, the shaft 92 will be permitted to rotate in the bushing 91, maintained in its orientation by rod 58; Spring 103 will act against flange 101 and plate 104, to resiliently urge the ball 102 of drive member 100 against the workpiece W,

the force of the spring being adjustable by manipulation of nut 99. Because there is less resistance between shaft 92 and bushing 91 than between any of the other parts of this construction, the orientation of the workpiece W relative to shaft 92 will be maintained.

The drive member 100 may act against either a workpiece directly, or against a pressure plate which is in contact with the workpiece.

In FIG. 15, there is illustrated another embodiment of the driver, there being shown the shaft 92 with the rod 58 pinned to it, the lower end of rod 58 being connected to a cylinder 106 having a fluid conduit 107 connected to it. Conduit 107, which is held to rod 58 by a clip 108,-is preferably an air conduit connected to a source of pressure 109 through a pressure regulator 110. A

piston 111 is contained in cylinder 106, and has a drive member 112 secured to it. Piston 111 is held in cylinder 106 by a cap 113 secured to cylinder 106. The piston 111 has a suitable amount of axial play or travel in cylinder 106, which may be approximately one-half inch. Any suitable means may be provided, if necessary, to prevent rotation of piston 111 within cylinder 106.

In operation, the spindle 48 and shaft 92 arelowered so that drive member 112 engages the workpiece W, or a suitable pressure plate interposed therebetween, and

is held in position by latch 84. Then air is admittedv into cylinder 106 to resiliently urge drive member 112 against the workpiece W (or a pressure plate).

The size of the cylinder 106 and the pressure of the fluid may be selected to obtain an optimum force through drive member 112. Also, piston 111 could take the form of a metal diaphragm or a rubber diaphragm which may be faced with metal.

In FIG. 16, there is shown an article 115 for abrading or lapping, similar to the table 38, and may be used as the table 38. It comprises a firm back-up member 116 having a flat surface 117 on which is a layer or sheet 118 of plastic material of a generally soft pliable nature such as polyethylene or vinyl. Sheet 118 is of uniform thickness. The edge 119 of plastic sheet 118 is beveled. Of course, the back-up member 117 may have a beveled edge. A lubricant comprising water and soap or detergent is used.

The above construction enables the wear ofabrading to be borne by the plastic sheet 118, and prevents wearing, including uneven wearing, of the back-up member 116. Typically, the back-up member 116 is a master, having a highly accurate flat surface 117, and the plastic sheet 118 not only takes the wear, instead of the master, but accurately transfers the precision of the master to the workpiece. Also, any unevenness present in the master may be compensated for by the sheet 118. The beveled edge permits the workpiece to cross the edge without scratching.

In FIG. 17, there is shown an article 120 comprising the back-up member 116 on which are plural uniform soft plastic layers 121 and 122, the bottom layer 121 being of a slightly smaller diameter to obtain thereby a relieved edge for the upper layer 122, which contacts the workpiece.

FIG. 18 discloses an abrading article in accordance with the present invention, such as article 115, having a fluent abrading material 123 thereon. Material 123 may be any of the known grinding, polishing or lapping materials, but advantageously is a completely dry abradant grain. The construction enables the plastic to hold the grain, the workpiece sliding over it and being cut or reduced by the grain. With the grain embedded in the plastic sheet 118, when pressure is applied, the abrasive grain is not crushed, resulting in a long preiod of use of each application of the abrasive. The abrasive grain (or polishing compound), being embedded in the plastic, thereby permits the maintenance of a highly accurate surface, more accurate than with abrasive cloth or paper. Also, it is not subject to the wear experienced with a stone or metal lap.

While the back-up member is shown with a flat surface, for some uses other surfaces may be used.

In FIG. 19, there is shown an article 125 comprising a back-up member 116, a plastic sheet 118, and a flexible abradant web 126, which may be either abrasive cloth or abrasive paper. This construction, with one or more sheets 118, surprisingly gives superior results, possibly due to a cushioning action given by the plastic sheet 118.

There has been provided a superior method of abrading which permits more rapid and accurate working than known methods. One machine suitable for carrying out the method is shown, the machine providing the necessary motion and having improved workpiece contacting apparatus.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention and therefore the invention is not limited to what is shown in the drawings and described in the specification but only as indicated in the appended claims.

What is claimed is:

1. A method of abrading a workpiece on a planar active abrading surface, comprising the steps of:

placing a workpiece to be abraded upon said abrading surface with a surface of said workpiece contacting said active abrading surface;

applying pressure to said workpiece to press said workpiece surface against said active abrading surface; rotating said abrading surface about an imaginary central axis; revolving said workpiece about said imaginary central axis as said abrading surface rotates; and,

preventing said workpiece from rotating about its own axis while it revolves about said imaginary central axis, thereby maintaining said workpiece in substantially fixed orientation even while said workpieces surface is being abraded by said active abrading surface.

2. A method as defined in claim 1 wherein only a portion of said workpiece surface contacts said active abrading surface with the remainder of said workpiece surface extending beyond the periphery of said active abrading surface.

3. A method as defined in claim 2 wherein said portion of said workpiece is always at least one-half of said workpiece surface.

References Cited by the Examiner UNITED STATES PATENTS 451,509 5/1891 MacLean 51358 1,049,983 1/1913 Bogdantfy 5128l 1,217,593 2/1917 Graft 51-407 1,520,662 12/ 1924 Maynard et al. 51-131 1,609,963 12/ 1926 Robinson 51-131 X 2,080,880 5/1937 Schenk 51131 2,434,614 1/ 1948 Hicks 51209 X 2,653,422 9/ 1953 Roshong et al. 51131 2,722,785 11/1955 Porter et al. 5ll31 2,737,454 3/1956 Danec 51309 2,757,491 8/1956 Galey. 2,828,197 3/ 1958 Blackmer 51-309 2,922,264 1/ 1960 Mushrush 51-281 2,958,166 11/1960 Foland 51358 3,019,570 2/ 1962 Olton 51-378 3,050,910 8/ 1962 Lichtenfeld 51-131 X LESTER M. SWINGLE, Primary Examiner. 

1. A METHOD OF ABRADING A WORKPIECE ON A PLANAR ACTIVE ABRADING SURFACE, COMPRISING THE STEPS OF: PLACING A WORKPIECE TO BE ABRADED UPON SAID ABRADING SURFACE WITH A SURFACE OF SAID WORKPIECE CONTACTING SAID ACTIVE ABRADING SURFACE; APPLYING PRESSURE TO SAID WORKPIECE TO PRESS SAID WORKPIECE SURFACE AGAINST SAID ACTIVE ABRADING SURFACE; ROTATING SAID ABRADING SURFACE ABOUT AN IMAGINARY CENTRAL AXIS; REVOLVING SAID WORKPIECE ABOUT SAID IMAGINARY CENTRAL AXIS AS SAID ABRADING SURFACE ROTATES; AND, PREVENTING SAID WORKPIECE FROM ROTATING ABOUT ITS OWN AXIS WHILE IT REVOLVES ABOUT SAID IMAGINARY CENTRAL AXIS, THEREBY MAINTAINING SAID WORKPIECE IN SUBSTANTIALLY FIXED ORIENTATION EVEN WHILE SAID WORKPIECES SURFACE IS BEING ABRADED BY SAID ACTIVE ABRADING SURFACE. 